I knew _____(少) about English when I first came to America. So I went to a _____（语言）school every day to learn English. One day, _____（在…期间the break, I asked one of my_______（同班同学） a question that I didn't understand. When I ________（感谢） her for it, she said, "You are welcome. It's a piece of cake." I thought to ______（自己）; America is really a society for money.  ______(一切)is done for pay there. So I said to her, "I haven’t  ____（拿来）any piece of cake with me today. What about a piece of biscuit?" She looked at me in _______(惊讶), then smiled. Then she realized that I hadn’t understood her. She said, "What I mean  is 'no problem'. "Then I came to learn that "a piece of cake" is not only a piece of cake, but also means a thing that is very ______（容易）.